Absorbent wearing article and process of making the same

ABSTRACT

An absorbent wearing article including an air permeable and liquid-impervious backsheet and a liquid-retentive absorbent structure placed on the backsheet. An outer sheet has having elastic members is placed on and bonded to a surface of the backsheet opposed to its surface bonded to the absorbent structure. The outer sheet has the elastic members intermittently bonded under tension thereto, and is formed in a region thereof facing the absorbent structure with an opening. The elastic members extend laterally under tension from a peripheral edge of the opening beyond the absorbent structure and the first backsheet is exposed through the opening.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional application of U.S. patent applicationSer. No. 11/942,948, filed Nov. 20, 2007, which claims priority under 35U.S.C. §119 to Japanese Patent Application No. 2006-326231, filed Dec.1, 2006, the contents of which are incorporated herein by reference intheir entirety.

BACKGROUND OF THE INVENTION

The present invention relates to an absorbent wearing article andparticularly to such an article including elastic memberscircumferentially extending around front and rear waist regions of thewearer (referred to hereinafter sometimes as fit gathers).

There have already been proposed absorbent wearing articles providedwith the fit gathers circumferentially extending around the front andrear waist regions to improve fit of the article around the wearer'swaist.

For example, Japanese Unexamined Patent Application Publication No.2002-95692, which is hereby incorporated by reference in its entiretyherein, discloses an absorbent article comprising a liquid-pervioustopsheet, a liquid-impervious backsheet and a liquid-retentive absorbentstructure interposed between these two sheets so as to define a frontwaist region, a rear waist region and a crotch region wherein the frontwaist region and/or the rear waist region is or are provided with aplurality of waist elastic members extending in a transverse directionat predetermined intervals. In a region occupied by the absorbentstructure, these waist elastic members have elasticity thereofrestrained and, outside the opposite side edges of the absorbentstructure, these elastic members are fixed to the components of theabsorbent wearing article by means of first fastening means so that theelasticity thereof is activated. In the vicinity of borders definedbetween the regions in which the elasticity is restrained and theregions in which the elasticity is activated, the waist elastic membersare fixed to the components of the absorbent article by means of secondfastening means.

In the absorbent article disclosed in the aforesaid Publication, thewaist elastic members are interposed between two sheets and a tensilestress as well as a draw ratio at which the waist elastic members areattached to the article can be freely determined so that the absorbentarticle such as a disposable diaper improved in fit, absorption capacityand leakage barrier performance may be provided. However, according tothe technique disclosed in the aforesaid Publication, the waist elasticmembers are not bonded to those two sheets in the region occupied by theabsorbent structure and cut off so that the elasticity of the waistelastic members is not activated. In the vicinity of borders definedbetween the regions in which the elasticity is restrained and theregions in which the elasticity is activated, the waist elastic membersare fixed to the components of the absorbent article. With sucharrangement, the segments of the waist elastic members having theelasticity restrained are left to contract and to be shortened. Thosetwo sheets are free from the contraction and left to cover the absorbentstructure.

Consequentially, the air permeability of the absorbent structure to theambient air may be deteriorated due to two sheets covering the absorbentstructure. In addition, a graphic or logo sometimes printed on the frontwaist region or the rear waist region of the absorbent wearing articlemay lose a desired visual quality.

SUMMARY OF THE INVENTION

In view of the problems left by the prior art unsolved behind as havebeen described above, it is an object of the present invention toprovide an absorbent wearing article having fit gathers improved so thatan absorbent structure has a high air permeability to ambient air and agraphic or logo printed on the article maintains a high visual qualityand a process for making the same.

There are provided an absorbent wearing article and a process for makingthe same.

According to the first aspect of the present invention, an outer sheethaving elastic members and an area larger than that of a first backsheetis placed on and bonded to a surface of the first backsheet opposed toits surface bonded to an absorbent structure, the outer sheet has theelastic members intermittently bonded under tension thereto and isformed in a region thereof facing the absorbent structure with anopening, the elastic members extend laterally under tension from aperipheral edge of the opening beyond opposite side edges of theabsorbent structure and the first backsheet is exposed through saidopening.

According to the second aspect of the present invention comprises thesteps of continuously feeding continuous elastic members in a directionparallel to a machine direction to continuous outer sheet continuouslyfed in the machine direction while the continuous elastic members areintermittently bonded under tension to the continuous outer sheet,making cuts extending orthogonally to the machine direction in thecontinuous outer sheet having the continuous elastic members bondedthereto so that the continuous elastic members are at least partiallychopped off, and bonding the side of the absorbent structure facing thefirst backsheet to the continuous outer sheet.

According to the present invention, the outer sheet including theelastic members (so-called fit gathers) is formed in its region opposedthe absorbent structure with the opening through which the firstbacksheet is exposed so that the first sheet is exposed directly toambient air. In this way, the absorbent wearing article assuring a highair permeability of the absorbent structure to ambient air. In additionto such high 20 air permeability of the absorbent structure, a graphicor logo may be printed on the first backsheet assures its visual qualitybecause the first backsheet is exposed through the opening as haspreviously been described.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will become more readily apparent from the DetailedDescription of the Invention, which proceeds with reference to thedrawings, in which:

FIG. 1 illustrates a diaper developed and flattened;

FIG. 2 schematically illustrates the diaper in a sectional view taken inparallel to elastic members; and

FIG. 3 schematically illustrates a process for making the diaper.

In the figures, elements that are repeatedly illustrated areconsistently identified by a single reference numeral.

DETAILED DESCRIPTION OF THE INVENTION

Taking a diaper 1 as an example, an embodiment of the absorbent wearingarticle according to the present invention will be described withreference to the accompanying drawings wherein FIG. 1 is a plan view ofthe diaper 1 developed and flattened as viewed from its outer surface,i.e., its surface opposed to its surface facing the wearer's skin andFIG. 2 is a sectional view taken along the line II-II in FIG. 1.

The diaper 1 developed and flattened has a shape which is symmetricabout a center line M and divided by invisible lines extendingorthogonally to the center line M to define a front waist region II, acrotch region 12 and a rear waist region 13 in this order. Referring toFIG. 1, an outer sheet 5 formed with an opening 7 and a first backsheet2 is exposed in this opening 7.

The first backsheet 2 is smaller than the outer sheet 5 and an absorbentstructure 3 having an area smaller than that of the first backsheet 2 isbonded to the backside of the first backsheet 2. In the front waistregion 11 and the rear waist region 13, the outer sheet 5 is provided onthe backside thereof with elastic members 4 comprising a plurality ofrubber strings extending under tension orthogonally to the center line Mso that a fit of the diaper 1 around the diaper wearer's waist may beimproved.

The opening 7 extends in the crotch region 12 and further into the frontand rear waist regions 11, 13 symmetrically about the center line M. Theabsorbent structure 3 bonded to the first backsheet 2 also extends in amanner similar to the opening 7 so as to cover this opening 7. On bothsides of the absorbent structure 3, the elastic members 4 laterallyextend under tension from a peripheral edge 8 of the opening 7 beyondthe opposite side edges of the absorbent structure 3. In the opening 7,the first backsheet 2 and a graphic printed thereon is exposed. Thoughnot illustrated, it is possible to divide the opening 7 in two or morezones unless the graphic is partially masked.

FIG. 2 is a schematic sectional view of the diaper 1 taken along theline II-II, i.e., along the elastic members 4.

The outer sheet 5 of the diaper 1 comprises a second backsheet 5A and anouter covering sheet 5B. The elastic members 4 are sandwiched betweenthese two sheets 5A, 5B and intermittently bonded thereto by means ofhot melt adhesive HM. The absorbent structure 3 is bonded through theintermediary of the first backsheet 2 to the second backsheet 5Aconstituting the outer sheet 5 by means of hot melt adhesive HM.

Each of the first backsheet 2, the second backsheet 5A and the outercovering sheet 5B is made of a breathable and liquid-resistant orliquid-impervious sheet wherein the outer covering sheet 5B defines theoutside of the diaper 1. A liquid-pervious topsheet 14 facing thewearer's skin is placed on and bonded to the second backsheet 5A and theabsorbent structure 3. More specifically, the topsheet 14 isintermittently bonded to the absorbent structure 3 by means of hot meltadhesive HM. While the topsheet 14 is provided with members of wellknown art such as leakage barrier cuffs and rubber strings serving toimprove a fit of the diaper 1 around the wearer's waist and legs,details of these members will be neither described nor illustratedherein.

The first backsheet 2 and the second backsheet 5A are bonded to eachother so as to surround the opening 7 and thereby to avoid anapprehension that body waste such as urine might leak through a gapbetween these two sheets 2, 5A. Preferably, the peripheral edge 8 of theopening 7 is fully bonded to the first backsheet 2. An area of theopening 7 is dimensioned to be smaller than an area of the absorbentstructure 3. Preferably, the opening 7 is formed in a manner that theperipheral edge 8 of the opening 7 is as close as possible to theperipheral edge of the absorbent structure 3 with a margin for bondingleft and thereby the opening area is maximized.

As will be apparent from FIG. 2, the elastic members 4 extend undertension to the peripheral edge 8 of the opening 7. Compared to the casein which the elastic members 4 are cut between the second backsheet 5Aand the outer covering sheet 5B and contracted these two sheets, it ispossible for the construction illustrated by FIG. 2 to obtain the largeropening 7. Thus the first backsheet 2 having the absorbent structure 3bonded thereto is exposed through the opening 7 and the area of thefirst backsheet 2 adapted to come in contact with ambient air withoutbeing masked by the outer sheet 5 can be maximized. Consequentially, ahigh permeability of the absorbent structure 3 to ambient air is ensuredand a high visibility of the graphic 15 printed on the first backsheet 2is also ensured since there is nothing which might mask the graphic 15(See FIG. 1).

The elastic members 4 extend under tension in a direction along whichthese elastic members 4 bear away from the absorbent structure 3 and,more preferably are extend outward under tension in a direction which isorthogonal to the center line M so as to strain not only the firstbacksheet 2 itself but also the absorbent structure 3 through theintermediary of this first backsheet 2. Consequentially, it is neitherapprehended that the graphic 15 might get wrinkled so as to lose itsinitial shape as well as its visual quality nor apprehended that theabsorbent structure 3 might get wrinkled and body waste such as urinemight leak through such wrinkles. In this regard, it is not essentialfor the present invention to bond the first backsheet 2 directly to theabsorbent structure 3 so far as the first backsheet 2 displaying thegraphic 15 is free from getting wrinkled. However, even if the firstbacksheet 2 is indirectly bonded to the absorbent structure 3, theabsorbent structure 3 is preferably bonded to the topsheet 14 and/or thesecond backsheet 5A.

FIG. 3 schematically illustrates a process according to the presentinvention for making the diaper 1.

The process according to the present invention basically comprises thesteps of continuously feeding continuous elastic members 40 comprising aplurality of rubber strings in a direction parallel to a machinedirection MD to a continuous outer sheet 50 continuously fed in themachine direction MD while the continuous elastic members 40 areintermittently bonded under tension to the continuous outer sheet 50,making cuts extending orthogonally to the machine direction MD in thecontinuous outer sheet 50 having the continuous elastic members 40bonded thereto so that the continuous elastic members 40 are at leastpartially chopped off and bonding the side of the absorbent structure 3facing the first backsheet 2 to the continuous outer sheet 50.

The center line M of the diaper 1 obtained by this process is orthogonalto the machine direction MD. The topsheet 14 (which is continuous in themachine direction MD) and the other members (not illustrated in FIG. 3)are bonded, in subsequent steps, to the continuous outer sheet 50 havingthe absorbent structure 3 bonded thereto and then the assembly obtainedin this manner is cut into the individual diapers 1 as finishedproducts.

The process according to the invention starts with continuously feedingthe continuous elastic members 40 and bonding to the sections of thecontinuous outer sheet 50 destined to define the front waist regions 11and the rear waist regions 13. The continuous outer sheet 50 comprisesthe continuous second backsheet 50A and the continuous outer coveringsheet 50B placed on and bonded to the continuous second backsheet 50Awherein the continuous elastic members 40 are fed so as to be interposedbetween the continuous second backsheet 50A and the continuous outercovering sheet 50B. Bonding of the continuous elastic members 40 to theouter sheet 50 is achieved by intermittently coating the continuousouter covering sheet 50B with hot melt adhesive HM using a firstadhesive coater 23 (not shown) and then placing the continuous elasticmembers 40 and the continuous second backsheet 50A. Raw fabric for thecontinuous second backsheet 50A and the continuous outer covering sheet50B are fed from respective rolls 150A, 150B.

In the next step, the cuts 20 each rectilinearly extending in thedirection parallel to the center line M from the front waist region 11to the rear waist region 13 are made by the cutter 24. As a result, thecontinuous elastic members 40 are at least partially cut off and thecontinuous elastic members 40 extending between each pair of theadjacent cuts 20 contract together with the continuous outer sheet 50 soas to form the opening 7. At this moment, the continuous outer sheet 50remains under a tension which is effective in the direction parallel tothe machine direction MD and therefore the continuous elastic members 40extending between each pair of the adjacent cuts 20 can not fullycontract, i.e., remain in a stretched state.

The shape of the opening 7 may be adjusted by appropriately selectingfactors such as draw ratio at which the continuous elastic members 40are feed as well as tension acting upon the continuous outer sheet 50.Instead of making the cuts 20 in the rectilinear fashion, the cuts 20may be made so as to cut out partially the continuous outer sheet 50 andthereby the shape of the opening 20 may be adjusted. While the openingarea of the opening 7 defined by the peripheral edge 8 thereof should besmaller than that of the absorbent structure 3 as has previously beendescribed, the shape of the opening 7 is preferably adjusted so that theperipheral edge 8 of the opening 7 may be as close as possible to theperipheral edge of the absorbent structure 3 and the opening are may bemaximized.

Then the first backsheet 2 having the absorbent structure 3 bondedthereto is bonded to the continuous second backsheet 50A by means of hotadhesive HM so that the first backsheet 2 may cover the opening 7.

The absorbent structure 3 and the first backsheet 2 are bonded to eachother in the other step and this assembly obtained in this manner is fedin the state of web in preparation for individually cutting. Theabsorbent structure 3 having the first backsheet 2 bonded thereto is cutby an absorbent structure cutter 25 into individual assemblies by anabsorbent structure cutter 25 and opposite side edges extendingorthogonally to the machine direction MD of the first backsheet 2 cut inthis manner are coated with hot melt adhesive HM by a second adhesivecoater 26. The first backsheet 2 may be previously printed with thegraphic 15 or logo (not shown).

The absorbent structure 3 is bonded to the first backsheet 2 so as tocover the opening 7 and thereupon the peripheral edge 8 of the opening 7is fixed in place by means of hot melt adhesive HM applied on theopposite side edges 27 of the first backsheet 2. In this way, theopening 7 is maintained in an opened state and the continuous elasticmembers 40 are maintained in a stretched state.

If a clearance is left between the peripheral edge 8 of the opening 7and the first backsheet 2, there may be provided an additional step ofbonding using heat welding technique such as heat sealing techniqueafter the absorbent structure 3 has been bonded to the continuous secondbacksheet 50A.

Alternatively, the process may include the step of coating thecontinuous outer sheet along the region in which the cuts 20 are to bemade inclusive of components extending orthogonally to the machinedirection MD with hot melt adhesive. More specifically, on both sides ofthe region in which the cut 20 is to be made i.e., regions destined tobecome the peripheral edge 8 may be previously coated with hot meltadhesive HM. In this case, a third adhesive coater (not shown) may beprovided on upstream (in the direction opposite to the machine directionMD) of the cutter 24. To avoid a problem that hot melt adhesive mightinterfere with operation of making the cut 20, a quantity of hot meltadhesive to be coated is preferably limited. Proper quantity of hot meltadhesive HM to be coated may be experimentally adjusted, for example, toa range of 1 to 3 g/m².

In this way, the first backsheet 2 can be bonded to the absorbentstructure 3 with hot melt adhesive HM extending along the peripheraledge 8 of the opening 7 and thereby the peripheral edge 8 can be fixedin place. A quantity of hot melt adhesive HM to be coated on the firstbacksheet 2 in the subsequent step can be reduced or eliminate the usethereof.

As stock materials for various sheets such as the continuous backsheet50A, the continuous outer covering sheet 50B and the first backsheet 2,the materials conventionally used in this technical field includingnonwoven fabrics, films or breathable films each made of thermoplasticresins may be selectively used. Bonding of these sheetsto the continuouselastic members 40 may be carried out by means of hot melt adhesive HMor heat sealing technique. When hot melt adhesive is used, anyparticular pattern of coating is not specified and the coating patternsuch as stripe-, spiral- or dotted-pattern may be selectively used. Tomake cuts 20, the cutting means of well known art such as rotary cutter,heat seal cutter supersonic cutter or water jet cutter may beselectively used.

Instead of using a plurality of rubber strings as the continuous elasticmembers 40, a single elasticized plastic film or elasticized nonwovenfabric may be used in the place of the continuous elastic members 40. Inthis case, the peripheral edge 8 of the opening 7 in the continuousouter sheet 50 may be bonded together with the single nonwoven fabric orthe like used in the place of the continuous elastic members 40 to thefirst backsheet 2 by means of heat sealing technique or hot meltadhesive HM. When the elastic members 4 is replaced by the singlenonwoven fabric or the like, such nonwoven fabric or the other is morereliably prevented from peeling off from the peripheral edge 8 of theopening 7 than in the case of the elastic members comprising a pluralityof rubber strings even when such nonwoven fabric or the like contract.In the diaper 1 obtained by the process as has been described above, thecontinuous outer sheet 50 having the continuous elastic members 40bonded thereto is formed on its side facing the absorbent structure 3with the opening 7 through which the first backsheet 2 of the absorbentstructure 3 is exposed. The opening 7 allows the first backsheet 2bonded to the absorbent structure 3 to be directly exposed to ambientair. In this way, the diaper 1 is provided, in which a high airpermeability of the absorbent structure 3 to the ambient air is ensured.Furthermore, the first backsheet 2 exposed in this manner ensures thatthe graphic 15 or logo printed thereon maintains a high visibilitythereof.

Furthermore, this process allows the continuous outer sheet 50 undertension to be stretched in the direction parallel to the machinedirection MD at the moment of making the cuts in the continuous outersheet 50. In other words, the continuous outer sheet 50 is stretched outto the width of the diaper 1 as the finished product. Consequentially,it is possible to reduce a dimension (as measured in the machinedirection) of the raw fabric fed from the roll destined to become awidth dimension of the individual diaper 1 with respect to the widthdimension of the individual diaper 1. Compared to the case in which nostep of making cuts is included, the production rate can be improved andthe production cost can be reduced on the assumption that the rate offeed is maximized.

It is also possible to make a plurality of cuts 20 extending along thecenter line M. For example, if tow cuts 20 spaced from each other alongthe center line M to form two openings 7, regions of the continuousouter sheet 50 which are continuous in the machine direction MD of thecontinuous outer sheet 50 can be increased and running of the continuousouter sheet 50 can be stabilized so that the continuous outer sheet 50can be easily handled.

It is within the scope of the present invention to include allforeseeable equivalents to the elements of the present invention asdescribed with reference to FIGS. 1-3. The examples provided are not tobe interpreted as limiting the invention beyond what is claimed.

1. A process for making an absorbent wearing article including an airpermeable and liquid-impervious first backsheet and a liquid-retentiveabsorbent structure placed upon said first backsheet, comprising thesteps of: continuously feeding continuous elastic members in a directionparallel to a machine direction to a continuous outer sheet continuouslyfed in said machine direction while said continuous elastic members areintermittently bonded under tension to the continuous outer sheet;making cuts extending orthogonally to said machine direction in thecontinuous outer sheet having said continuous elastic members bondedthereto so that said continuous elastic members are at least partiallychopped off; and bonding the side of said absorbent structure facingsaid first backsheet to said continuous outer sheet.
 2. The process formaking the absorbent wearing article according to claim 1, wherein: saidabsorbent wearing article is symmetric about a center line when saidabsorbent wearing article is developed in a flattened state; saidabsorbent wearing article comprises a front waist region, a crotchregion and a rear waist region in this order as viewed in a directionorthogonal to said center line; said center line is orthogonal to saidmachine direction of said continuous outer sheet; said continuouselastic members are fed to said front waist region and said rear waistregion; said cuts are made in a direction parallel to said centerline soas to extend from said front waist region to said rear waist region; andthe first backsheet of said absorbent structure is bonded to said outersheet from said front waist region to said rear waist region so as tocover said opening.
 3. The process for making the absorbent wearingarticle according to claim 1, including a step of coating the regionsalong which said cuts are made with hot melt adhesive in the directionorthogonal to said machine direction before the step of making the cutsin said continuous outer sheet.
 4. The process for making the absorbentwearing article according to claim 1, wherein: said outer sheetcomprises a continuous second backseet bonded to said first backsheetand a continuous outer covering sheet bonded placed upon and bonded tosaid second backsheet; said continuous elastic members are interposedbetween said continuous second backsheet and said continuous outercovering sheet and bonded thereto; and said first backsheet on a side ofsaid first backsheet is bonded to said continuous second backsheet. 5.The process for making the absorbent wearing article according to claim1, including a step of making a plurality of cuts spaced one fromanother along said machine direction for forming a plurality ofindividual diapers from said continuous outer sheet, continuous elasticmembers and a plurality of absorbent structures.